Non-volatile semiconductor memory devices, such as flash memory cards and the like, have become an essential component for digital information storage in modern electronic devices. In particular, modern portable electronic devices benefit greatly from the high-capacity, versatility, ruggedness, and power utilization efficiency afforded by semiconductor memory devices. Such modern portable electronic devices may include, by way of example, digital cameras, digital music players, smart phones, video game consoles, portable computing devices, among others.
Flash memory storage cards may be fabricated as a system-in-a-package (SIP) or as a multichip module (MCM), in which multiple semiconductor die are mounted and interconnected on a substrate. The substrate may include a rigid, dielectric base with a conductive layer etched on one or both sides. The die are electrically connected to the conductive layer(s) of the substrate. In turn, the conductive layer(s) of the substrate provide for electrical connection of the die to a host electronic device. Following electrical connection of the die to the conductive layer(s) of the substrate, the die/substrate assembly may be encased in a protective material, which also assists in holding the die and substrate together.
Connection of the die to the substrate can include connection of electrically conductive pads on the die to wire bonds on the substrate. The connections between the pads of the die and the wire bonds of the substrate are often inaccessible for continuity testing once the die is placed on the substrate, and especially after the die and substrate are encased in the protective material. For product testing purposes, it is desirable to have an ability to test the electrical continuity between each pad of the die and the corresponding wire bond of the substrate to which the pad should be electrically connected. It is within this context that the present invention arises.